Disc drives are commonly used in workstations, personal computers, portables and other types of computer systems to store large amounts of data in a form that can be made readily available to a user. In general, a disc drive comprises one or more magnetic discs that are rotated by a spindle motor at a constant high speed. The surface of each disc is divided into a series of data tracks which are spaced radially from one another across a band having an inner diameter and an outer diameter. The data tracks extends generally circumferentially around the discs and store data in the form of magnetic flux transitions within the radial extent of the tracks on the disc surfaces. Typically, each data track is divided into a number of data sectors that store fixed sized data blocks.
A head includes an interactive element such as a magnetic transducer which senses the magnetic transitions on a selected data track to read the data stored on the track, or to transmit an electrical signal that induces magnetic transitions on the selected data track to write data to the track. The head includes a read/write gap that positions the active elements of the head at a position suitable for interaction with the magnetic transitions on the data tracks of an associated disc as the disc rotates.
Each head is mounted to a flexure/gimbal assembly which in turn extends from a rotary actuator arm so as to be selectively positionable over a preselected data track of the disc to either read data from or write data to the preselected data track. The head includes a slider assembly having an air bearing surface that causes the head to fly over the data tracks of the disc surface on an air bearing established by air currents set up by the rotation of the disc.
Typically, several discs are stacked on top of each other and the surfaces of the stacked discs are accessed by the heads mounted on a complementary stack of actuator arms which compose an actuator assembly. The actuator assembly generally includes head wires which conduct electrical signals from the heads to a flex circuit, which in turn conducts the electrical signals to a printed circuit board (PCB) mounted to a disc drive base deck.
A continuing trend in the disc drive industry is to increase the data storage capacities in successive generations of drives while maintaining or reducing the physical sizes of the drives. As a result, interdisc spacings and areal densities are continually increasing, providing increased sensitivity to external vibration inputs, self-excitation of rigid body vibration modes and warpage when the drives are mounted in a fixture or system.
Previous generations of disc drives typically utilized vibration isolation devices such as shock mounts (grommets) within the disc drive mounting envelope to isolate the drives from such effects, as disclosed for example in U.S. Pat. No. 5,140,478 issued Aug. 18, 1992 to Yoshida. As will be recognized, these devices provide vibration isolation for selected frequencies and additionally protect disc drive base decks from warpage.
However, associated problems with such devices include the degradation of mechanical shock resistance and the requirement for significant amounts of sway space (that is, the space allocated to allow movement of a disc drive housing in the event of a mechanical shock to the drive). As understood by those skilled in the art, the sway space requirement significantly affects the design of a drive because the disc drive space envelope includes not only the physical space occupied by the drive, but also the associated sway space of the drive. Thus, both the physical size of the drive as well as the associated sway space must fit within the available space for the drive in a given mounting environment (such as, for example, within a disc drive bay in a personal computer).
Accordingly, the general trend in the industry is to move away from the use of such isolation devices in favor of no external isolation protection beyond the basic structure of the disc drive housing. While such an approach has generally been found to provide stiffer drive mounting, thereby increasing mechanical shock resistance and facilitating greater track densities, there remains a risk that high frequency vibrations caused by the rotation of the discs may excite resonances in the mounting environment sufficient to generate undesirable acoustic noise and adversely affect servo operation of the drive.
Accordingly, as disc drive data storage and transfer requirements continue to increase, there remains a continual need for advancements in the art whereby disc drives can be provided with sufficient mechanical shock resistance and mounting environment isolation to meet low sway space requirements and to facilitate reliable operation of the drives.